siemens



2 Sheets-Sheet l. C. W. SIEMENS.

ELECTRIC LAMP.

No. 255,466. Patented Mar. 28,1882r Www-Ses. 172 M972 fw.

2 Sheets-Sheet 2.

C. W. SIEMENS.

ELEGTRIG LAMP.

Patented Mar. 28, 1882f UNITED STATES PATENT OFFICE.

CHARLES V. SIEMENS, F QUEEN ANNES GATE, WESTMINSTEB, ENGLAND.

ELECTRIC LAMP.

kSPECIIEICATION forming part of Letters Patent No. 255,466, dated March28, 1882.

Application filed September 1G, 1879. Patented in England May 27, 1870.

4To all whom fit may concern:

Beit known that I, CHARLES WiLLIAM SIE- MENS, of Queen Annes Gate,Vestminster, England, have invented an Improvement in Electric Lamps;and I do hereby declare that the following description, taken inconnection with the accompanying drawings, hereinafter referred to,forms a full and exact specification of the same, wherein I have setforth the na- 1o ture and principles ot' my said improvement,

2o tric arc.

by which my invention may be distinguished from others of a similarclass, together with such parts as I claim and desire to secure byLetters Patent-that is to say:

According to one part of my present invention, I cause the automaticadvance or feed of a stick or tube of carbon forming the one pole of anelectric lamp toward the other pole to be determined by the heatproduced by the elec- A thin strip of zinc or other fusible metal isfixed in a longitudinal groove in the carbon rod or cylinder, so as toproject slightly from its surface, the projecting edge of which stripbears against the stop on the carbonholder, so that as it is melted atsuch point by the heat from the electric are the carbon will bepermitted to advance. By this arrangement the distance from the point ofarrest to the. end of the carbons will be practically a 3o constantquantity, and consequently the gradual and uniform advance of the carbonwill be effected without clock-work or me ,hanieal regulators.

In order to provide for an uninterrupted feed of the carbon pole whilethe lamp is in operation,I fix on the end of each separate carbon rod abead of gum or saccharine matter, which, in approaching the point ofcombustion, becomes heated so as to be first fused and 4o thencarbonized, so as to form a junction bethe negative pole may consist ofa rod of steel or iron, which, in asimilar manner to the carbon pole, isfed forward by spring-power or gravity against a stop as the end thereofis melted and consumed by the voltaic arc. The

5o stop in this case consists of a hollow tubular 'holder of copper,through which water is made to circulate, so as to be maintained cool.rlhe tube through which the iron or steel rod is fed islarge enough toallow the rod to pass freely, but at or near the end. which is presentedto the other pole it is slightly reduced in diameter, so as to act as astop. rlhe electric are is found to concentrate upon the end of the rodin preference to the surrounding cooled copper holder, and the extremeend of the rod being thus intensely heated it softens and yields to thepressure urging it forward, and thus, like vthe carbon pole, it isadvanced in the measure of its consumption, which proceeds at aeomparatively slow rate. The vapor given ott' by the burning metal isfound to give definition and great brilliancy to the electric are, andin order still further to add color and brilliancy to the iiame, I insome cases make the iron or steel pole tubular, and fill it withtightlyrammed strontia, lime, manganese, or other earthy matter thatwill burn away with the iron.

The iron or steel rod or tube may also be provided with either acomplete coating or a project-ing tillet of zinc, similar to the carbonpole, which coating or fillet will bear against the tubular holder, andin melting away will allow the iron or steel rod or tube to be advancedthrough the holder, the contracted portion of which will in this case belarge enough to allow the rod or tube to pass through.

The distance ot' the two poles, and consequently the length of theelectric arc, is so regulated that the difference of potential betweenthe two poles is practically constant. For this purpose the holder ofeither the positive or the negative pole is attached to a lever that isacted upon by a thin wire or strip of metal of high resistance, soarranged in connection with the circuit that when the normal distance ofthe polesis maintained an inappreciable quantity of the current willpass through such wire or strip of metal without passing through thelamp; but when, through the increase of distance of the poles, theresistance of the electric arc is also increased, a greater portion ofthe current will pass through the thin wire or metal strip, which, inacting upon the lever, will cause this to move the pole carried therebynearer to the other pole, and thus restore the normal length of arc anddif- IOO ference of potential of the two poles. The wire or metal strip,in a stretched condition, is connected at one end or an intermediatepoint ot' its length by an insulated connection to the lever, so that onan increase of the quantity of the electric current passing through itit will become expanded by the increase of heat, and will allow thelever to move so as to approach the poles, while on a decrease of thecurrent passing through it., consequent 011 a too near approach of thecarbons, it will, in contracting, move the lever so as to separate thepoles.

On the accompanying drawings, Figure 1 shows avertical section of onemodification of my before-described improved lamp. Fig. 2 shows a planofthe same. Fig. 3 shows a crosssection on line X X, Fig. l.

The carbon rod A, constituting the positive pole, is carried in the irontubular holder B, supported by the levers C, having their fulcra on aninsulated bracket, D', of the fraining D, to which bracket the oneterminal, E, of the circuit-wire is connected. The other ends ot' thelevers G carry an ebonite roller, F, over which is led the loop of -athin metal wire or baud, G, ot' high resistance, arranged as follows:rlhe one end of the wire is tixed to an insulated bracket, H, and isthere put in electrical connection by means of a wire, G', with thecircuit-wire E. From the bracket H the wire passes down and round thelebonite roller I, and thence alternately up and down consecutively overthe ebonite rollers l' l2 13 I4, then over the roller F on the lever (l,and thence consecutiivelydown and up over the ebonite rollers l5 l6 I7I8 19 to the small barrel J in electrical connection with the casing D,to which barrel the other end of the wire is attached, and which can berotated by the tangent-screw J', so as to wind up the end ofthe wire Gmore or less round it. rlhe rollers I to 19 being carried in fixedbearings respectively at the upper and lower end ot' the casing D, itwill be seen that the winding of the wire upon the barrel J will causethe end ofthe double lever (l to be drawn more or less downward, thusadjusting the position ot the tube B and carbon pole A relatively to thenegative pole K, and also that any expansion or contraction ot' thewire, due to variations in its temperature, will cause the end ot' thelevers carrying the roller F to move up or down, and consequently willmove the pole A nearer to or farther from the pole K. The wire G ismaintained in a stretched condition by the weight of the carbon rods Aand holder B acting at the end of the levers C, and also by a helicalspring, L, bearing against the fixed guide D2for the holder, andpressing the lower end ofthe latter downward, which spring acts as adamper to prevent any jerking motion of the holder B when being moved upor down by the action of the wire G.

The carbon rods A, which fit loosely in the tubular holder B, have alongitudinal groove,

in which is tixed a thin strip of zinc or other fusible metal, M, whichat the lower end bears against a stop in the corresponding longitudinalslot of the tubular holder. This stop is at such a height above theextreme end of' the pole that the heat conducted from the electric arcthrough the carbon to such point will be just sufficient to fuse the endot' the zinc strip, which, in being thus gradually consumed,will allowthe carbon to descend gradually in proportion as it burns away. Theupper end ot' the carbon rod is recessed, as shown at A', and in suchrecess is a bead of gum or saccharine matter, so that when it, togetherwith the correspondinglyformed end of the following carbon, A2, whichfits closely thereon, arrives near the luminous arc the heat will firstfuse and then carbonize the gum, thus f'orining a carbonaceousjunctionbetween the two rods, and insuring an uninterrupted feed thereof.

The lower end of the tubular holder B is provided with a shield, B',with porcelain or other refractory coating, for protecting the spring Land zinc strip M from the radiated heat of the electric arc. Thenegative pole K consists in this case otl an viron rod which passes upthrough the hollow tubular copper holder N, through which water is madeto circulate from the tubular casing D, constituting a reservoir, thecold water passing from the bottom of the casing through the hollow armD3 to the lower end ot' N, and the heat-ed water ascending from theupper end of the latter through the tube D" to the upper end of thecasing D.` The latter has a considerable capacity compared with theholder N, and offers very extended surface for radiating the heat takenup bythe water, so that by the circulation a constantsupply ofsufficiently-cooled water is made to tlow into the holder. The iron rodpasses freely through the holder to the upper end, where the opening ot'the latter is slightly restricted by a platinum collar, so that, asbefore stated, the upper end of the rod, softened hy the intense heat ofthe electric arc, can just squeeze i tselt' upward through the holder asits extreme end is consumed away, the upward motion being afforded by acoiled spring, O, carried bythearm D, acting by means of a wire andhook, O', on the lower end of the rod K.

The action of the lamp is as follows: The electric current passes fromthe circuit-wire E through lever C and holder B to the carbon pole A,thence forming the electric arc tothe metal pole K, and through thetubular holder N, pipes D3 D4, and casing D to the other terminal, P. Solong as the distance of the carbon pole from the metal pole is such asto give the requisite dift'erenee of electric potential between the twonearly the whole of the current will pass in the direction indicated, asmall quantity, however, passing through the wire G' and thin stretchedwire G of high resistance to the casing D and terminal P without passingthrough the lamp. By such pas- IOO IOS

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sage of the current the wire Gr becomes heatl carbon poles of anelectric lamp have been ed, and consequently expanded to a certainextent, and its length is so regulated by the barrel J and screw J thatwith such normal degree of expansion it will hold the lever C and carbonpole in the normal position required. On a decrease of difference ofpotential between the two poles occurring, owingto a too near approachof the carbon pole, more of the current will pass through them and lessthrough the resistance-wire or by-pass G, and this, in contracting, willmove the lever C and holder B, so as to separate the carbon pole fromthe metal pole to such an extent as to restore the normal difference ofpotential. If, on the other hand, the carbon pole be removed too farfrom the metal pole, so as to increase the difference of potential abovethe normal degree, less of the current will pass through the poles andmore through the by-pass G, and the wire becoming heated, andconsesequently expanded beyond the normal degree, will allow the leverC- and carbon pole to descend, so as to restore the normal difference ofpotential. If the electric are shouldl be blown out or cease from anycause, then the by-pass wire, being the only channel for the current,will become rapidly heated and expanded to such an extent as to allowthe carbon pole to descend until it touches the metal pole. rIheelectric arc will instantly be rfa-established, and the electricpotential having now become a minimum, owing to the proximity of thepoles, the ley-pass wire will cool and contract until the normal lengthof arc has been re-established.

The wire Gr is made of considerable length, as shown, so that even aslight increase ot' temperature will give an appreciable elongation forthe purposes of regulation, as above described, the motion being furthermultiplied by the dierence in length of the two ends of the levers C.The by-pass wire or metal strip is contained within the hollowlamp-casing D, maintained at a practically uniform temperature by thecirculating water, so that the wire is not aected by sudden changesottemperature of the surrounding atmosphere. rllhe casing is suppliedwith water from time to time through the small side compartment, D5.

Having thus described the nature of my invention and in what manner thesame is to be performed, I wish it to be understood that I vdo not claimthe combination of two coils, one

ot` low resistance in the lamp-circuit and one otl high resistance,external to such circuit, operatingjointly for the regulation of thedistance ot the poles of the lamp, as described in the specication ofEnglish patents granted to me as communications from F. v. HefnerAlteneck on the 4th December, 1878, No. 4,949, and 1st July, 1879, No.2,652.

I am also aware that the extreme ends ofthe brought in contact withfafixed point-such as a block of limeand have been automatically fedforward as such extreme ends were consumed, and I do not claim such anarrangement as my invention; but

I claim- 1. A carbon rod constituting the pole of an electric lampprovided at its rear end with a bead ot' gum or saccharine matter, whichbecomes carbonized by the heat of the electric arc, so as to form acarbonaceous joint between the end ot' the rod and the contiguous end ofthe next one.

2. Aniron or steel rod constituting the negative pole ot' an electriclamp, in combination with a'holder containing acooling-liquid and aspring combined, as described, with said rod for the purpose of feedingit forward, as and for the purposes described.

3. In an electric lamp, the combination of the carbon pole A, holder B,lever C, thin metal strip or wire G, stretched over insulating-rollers FI, one end of the said wire or'metal strip being in electricalconnection with the one circuit-terminal, E, and the other end inconnection with the other circuit-terminal, P, of the lamp,substantially as herein described with reference to the accompanyingdrawings.

4. In an electric lamp, the combination of the iron or steel negativepole K, tubular holder N, containing a cooling-liquid, tubular arms D3D4, and lamp-casing D, constituting a waterreservoir, with extendedheat-radiatin g surfaces, operating substantially as herein described.

5. In an electric lamp, the combination ot` the tubular water-reservoircontaining within it the stretched thin metal strip or wire Gr,constituting a by-pass for the electric current, so that such metalstrip or wire is protected from sudden changes ot'temperature ofthesurrounding atmosphere.

6. A reciprocating carbon-holder open at the upper end to permit theinsert-ion ot` additional carbons to follow up the preceding` one,incombination with a carbon rod provided at its rear end with matter whichbecomes carbonized by the heat orn the electric are, whereby the carbonis rendered continuous without interrupting the light.

In testimony whereot1 I have signed my name to this specification, inthe presence of two subscribing witnesses, this Sth day of' August,1879.

C. WILLIAM SIEMENS.

Witnesses:

J. D. LACY, Clerk to Ridgway ttf Sons, 2 l/Vaterloo Place, Pall Mall, S.W.

CHARLES E. P. WILSON, Notarys Clerk, 2 llaterloo Place, Pall Ma ZI,London, S. W.

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